Electronic indicator



Feb. 14, 1950 R, STEINHOFF 2,497,190

ELECTRONIC INDICATOR Filed June 18, 1948 2 Sheets-Sheet l a f.; l Si 1I @xv-HI l and End/0 4 Feb. 14, 1950 1. R. STEINHOFF 2,497,190

ELECTRONIC INDcAToR Filed June 18, 1948 2 Sheets-Sheet 2 Svi.

Patented Feb. 14, 1950 UNITED STATES PATENT OFFICE 7 Claims.

This invention relates to electronic indicating instruments and more particularly to radio direction instruments whereby the direction of a known radio transmitting station is automatically shown by an indicating device operatively connected through radio receiving apparatus with a directional antenna array.

In an instrument of this character employing a directional antenna array of xed position relative to the radio receiving apparatus and indicating device, but all of which may be carried on a moving vehicle such as an airplane, individual directional elements of said directional antenna array must be switched or operatively connected in receiving sequence to the radio receiving and amplifying apparatus and in corresponding recurring sequence the output of the amplifying apparatus must be applied to the indicating instrument for proper direction showing. Mechanical commutation or switching has been employed for sequence switching, but mechanical switching entails diiliculties arising 1n part from lack of speed and contactor or circuit breaking troubles. The direct substitution of electronic switching for mechanical does not necessarily overcome important difculties in the operation of a direction indicating instrument.

It will be clear that the received radio signal strength of each individual antenna element of said directional antenna array must be truly represented and applied as a power magnitude on a corresponding element of the indicating device for accurate showing of the direction of the radio transmitter which is tuned in or received. The simpler and most easily read indicating devices such as an electro-mechanical device carrying a moving pointer commonly require appreciable power for operation where rugged and positive action is desired, yet this operating power must be adequately and accurately controlled with respect to the differential signal strengths of the individual elements of the directional antenna array. It is further important that a recurring sequence switching arrangement coupling in effect a particular directional antenna element received signal with a corresponding visual indicator actuating element, and thereby representing a continuous sampling of signal strength throughout 360 of direction, be eilective in action and free from time lag or lack of clearance with respect to succeeding switch steps or equivalent succeeding samples of signal strength.

With these requirements in mind, it is an object of this invention to provide an electronic 2 switching apparatus adapted to operatively couple radio receiving directional antenna elements in recurring sequence with corresponding elements of a visual indicating device.

Another object is to provide power operating circuits and apparatus controlled in correspondence with signal strength received on individual directional antenna elements.

A further object is to provide means for triggering successive tubes of an electronic switch adapted for power operation and low resistance circuit elements.

Still another object is to provide .individual directional antenna element activating rectiiier circuits having successively very low eilective resistance and very high eective resistance as controlled by potentials derived from said electronic switching apparatus.

These objects and other objects hereinafter set forth, are attained by the apparatus of the invention which will be more particularly described With reference to the accompanying drawings in winch:

Fig. 1 is a circuit diagram o! a radio direction nder embodying the invention;

Fig. 2 is a circuit diagram of a similar radio direction finder with modied apparatus embody the invention; and

Fig. 2a is a diagrammatic representation of a circuit and circuit elements which may be added to the apparatus of Fig. 2.

In the gures of the drawings, like reference characters indicate similar elements of the illustrated embodiments.

In Fig. 1, the reference characters A-D identify four loop or directional antennae arranged at to each other and each having one terminal connected by a common lead i to the usual tuned input transformer 2 of an ampliier tube 3 having an output coil 4 coupled, together with the coil 5 of a non-directional antenna 6, to the input coil l of a high-power electronic ampliiler-rectier unit 8. The rectified carrier output of the unit 8 is impressed upon a direct current amplifier tube 9 having a resistor I0 across which voltages are developed, as will be described later. that are proportional to signal inputs at the directional antennae A-D.

The other terminals of the several directional antennae are individually connected to ground through the selectively activated space discharge paths of diode rectiers Il, l2 and condensers Ca-Cd, respectively. A separate diode may be employed for each directional antennae circuit but it is convenient anddesirable to use double diode tubes of, for example, the 6H6 type. The terminals of the antennae A-D are connected to the cathode elements a-d of the diode elements and the corresponding anode elements are connected through leads I3a-I3d to the several stages or units I4a-I4d of the electronic switch assembly. The switch stages are of identical construction and each includes two triodes I5, I6 in series that may be combined in single envelopes I'Ia-I 1d, respectively. The 6SN'7GT type of twin triode has proved satisfactory, requiring the use of but four tubes for the switch system.

In each switch stage, the grid-cathode input circuits of the triodes I5, I6 are of identical design and include a transformer secondary winding L in series with a condenser C1, a resistor Ri being shunted across the grid and cathode elements. The primary winding L1 of each transformer is connected between the anode of the triode I5 of the next preceding stage and a source of energizing potential indicated by the character +Eb. The input windings L of the triodes I5 are directly connected to their cathodes While the input windings L of the triodes I6 are grounded and returned to their cathodes through cathode resistors I9 of for example 1000 ohms, that are in effect the plate current supply sources for the diodes II, I2. The leads I3a-I3d from the diodes Il, I2 are connected to the cathodes of the triodes I6 of the several switch stages I 4a-I4d, and the energizing potentials established on the anodes of the diodes II, I2 therefore vary with the voltage drops across their associated cathode resistors I9.

A further transformer winding L2, which may be wound upon the primary winding L1, is shunted by a condenser Cz and has one terminal connected to the cathode of the triode I5 through a resistor Rz, the other terminal being connected to the anode of the associated trode I6. Adjustable taps on the several resistors R2 are connected by leads a-20d to the direction indicating instrument I. These tapped connections are provided to permit adjustment for establishing the same potential on the several leads 20a-20d at zero signal input to the direct current amplier tube 9.

The instrument I includes stationary field windings energized in accordance with signal energy at the directional antennae A-D and a transversely magnetized rotor, not shown, carrying a pointer 2|: the rotor being of the permanent magnet type or of the electromagnetic type described in my prior applications Serial No. 417,835, filed Nov. 4, 1941, now Patent 2,392,420, Method of and apparatus for radio directional finding, and Serial No. 439,330, filed April 17, 1942, now Patent 2,376,730, Method of and apparatus for sonic detection. The rotor is not restrained by restoring springs but rotates freely through 360 in accordance with the voltages developed across the field windings 22a-22d. Windings 22a, 22h are serially connected between the leads 20a, 20h from switch stages Ida, I4b that are associated with the diametrically opposed directional antennae A, B; and windings 22c, 22d are similarly connected in series between the leads 20c, 20d. Condensers 23a-23d are connected between the several leads 20a-20d and the common lead 24 that is connected to the anode of the direct current amplifier Sand has a direct current potential that varies cyclically in accordance with the signal energy input at the several directional antennae A-D.

The instantaneous direct current potential across the resistor I0 is determined by the cardioid pattern resulting from the non-directional antenna 6 and the particular directional antenna then connected to ground by the electronic switching system. The instantaneous voltage impressed upon the common terminals of condenser 23a- 23d therefore varies cyclically as the several directional antennae are rendered operative in succession by the voltage drops across resistors I9 of switch stages Ila-I 4d as the latter are periodically rendered conductive. Steady or xed direct current voltages are serially impressed upon the opposite terminals of the Condensers 23a-23d through the individual leads 20a- 2 0d. The electronic switch system operates, in effect as a double pole, multiple throw switch to connect the directional antennae in sequence to the amplifier-rectifier unit 8 to impose upon one terminal of the associated Condensers 23a-23d a directionally significant Voltage, and simultaneously to switch a fixed voltage upon the other terminal of the particular condenser 23a--23d corresponding to the directional antennae A-D then energized. The switching frequency depends upon the constants selected for the timing condenser-resistor components of the switching system, as will be explained hereinafter, and it is convenient to employ a switching frequency of 20 cycles per second, i. e., each directional antenna is repeatedly connected to the indicating instrument for 1/0 of a second. A switching frequency of this order permits the simultaneous use of the antennae and amplifier system for the reception of signal intelligence as the loud-speaker or headphones may be designed, or by-passed, to eliminate disturbance from the cycles per second switching.

Each switch stage is energized, through its input transformer, by the collapse of the plate current of the preceding stage upon the completion of the charging of the condenser C2 of that stage. Each stage would resume its conductive condition upon the discharge of Condensers C1 through the associated resistors R1 but the circuit constants are so selected that the stages are tripped off in sequence at a frequency somewhat higher than that corresponding to their natural periods of recurring pulses. This precludes conduction simultaneously in two switch stages and prevents any stage from getting out of step. For a switching frequency of 2O cycles per second, appropriate values may be:

C1=0.002 microfarad C2=0.150 microfarad R1=5 megohms Each switch stage is either conductive or nonconductive as the control is of the on-off type and not of the modulating or progressive magnitude change type. This is a decided advantage as the timing action is not affected by variations in the mutual conductance values of the several triodes. The plate voltage distribution across the serially connected triodes of each stage is affected by mutual conductance variations but the direct current voltages impressed upon the condenser bank 23a-2 3d through leads 20a-20d may be equalized by adjustment of the voltage divider resistors Rz which, in one embodiment, had values of 1000 ohms. The plate supply to the anodes of the switching triodes I5 was 300 volts, and the taps of resistors R2 were adjusted to impress volts on the leads 20a- 20d as the switch stages were energized in sequence.

' The triode I6 of each switch stage may be classed as an oscillator or pulse generator, the plate being inductively coupled to the grid in such sense that an increase in plate current drives the grid more positively, thereby further increasing the plate current and driving the grid positively until it draws current to charge the condenser Ci. The condenser C2 causes the grid to continue to draw current for the length of time desired for each stage to remain conductive, the conductive period being longer as the capacity of condenser C2 is increased. When the plate current of a stage starts to decrease, the grids of tubes I5 and I6 of that stage are driven negative, thereby further decreasing the plate current until the grids are driven negative far beyond cutoff. This action also drives the grids of the next switch stage positive, thereby rendering the next stage conductive. The first stage remains nonconductive as the voltage across the condenser Ci slowly leaks off through the high resistance grid resistor R1, and the stage is tripped Ainto conductivity by the cutoi of the preceding stage before the blocking bias leaks off through resistor R1.

As described above, the windings of the direction indicating instrument I are connected to the condensers 23a-23d, and the several condensers are successively charged by the potential difference between the fixed voltage, for example, 150 volts in the particular embodiment above mentioned, applied through leads 20a-20d and the instantaneous voltage developed by the direct current amplier 9 across its output resistor I0. If one condenser 23a-23d of a pair associated with one connected pair of windings 22a- 22d has 100 volts across it and the other has 50 volts, there will be a 50 volt drop across the meter windings and current flows through the windings from one condenser to the other as the condenser voltages tend to equalize. Before this voltage equalization is attained, each condenser is again recharged to its original value and the recharging process is repeated continuously in cycles of such short duration that the equalizing current through the meter coils is substantially continuous. The indicating instrument pointer 2l assumes a position that is determined by the relative magnitudes and directions of the currents thus established in the instrument windings 22a-22d. The condensers 23a-23d may have values of 4 microfarads when the switching frequency is 20 cycles per second and the windings 22a-22d each have a resistance of 750 ohms. The voltage is applied to each condenser twenty times per second and this timing allows the 4 microfarad condensers to reassume their proper potential levels in about one-half the period during which each timing stage is conductive thereby maintaining the directionally-signicant differential potentials substantially independent of timing variations in the individual stages. The discharge paths of the differential potential between condensers 23a, 23h and between 2 3c, 23d are of relatively high resistance and the potential y diii'erences are not rapidly dissipated during the .short intervals between recharging of the condensers to the several potentials indicative of signal strength at the respective directional antennae.

It will be observed that the electronic switch of Fig. l comprising tubes Ila-I 1d and their associated circuits is capable of handling appreciable power and may be termed a power handling switch as contrasted with voltage operated electronic switches known in the art.

Tubes Ila-Hd are each dual triodes or their equivalent, which, when conducting, as occurs in sequence by grid voltage change, show a relatively low resistance to the now of current from the anode current supply +Eb and this relatively low tube resistance is adapted to handle the appreciable plate output power of tube 9. Other power circuit elements such as indicator windings 22a-22d, transformer windings L1 and I e, and resistors R2 and I9 have relatively low resistance values keeping the total power circuit resistance low and adapted for handling appreciable power and current values. Condensers 23a- 23d have a large capacity value adapted to steady the flow of power currents.

In addition to the new and useful amplified power output switching provided by the apparatus of Fig. l employing tubes Ila-IId, low impedance input circuit switching is provided in conjunction with the voltage activated rectiers represented by diode elements a, b. c and d of tubes II and I2. A conducting diode, as is represented, for example by diode a when tube Ila is conducting and a positive voltage derived from the cathode resistor I9 of tube I'Ia is impressed on the plate of diode a, shows a desirable low resistance or impedance for purposes as here employed for directional antenna element switching.

It may be further noted that in the electronic switch of Fig. 1, which comprises the series sequence of switch stages having tubes I la-Ild and associated circuits, the actual trigger voltage which operates each tube is derived from the breakdown of a magnetic eld set up by the preceding conducting tube in a transformer or equivalent magnetic winding. Since the electronic switch of Fig. l is current or power operated rather than one of the familiar voltage operated types, the appreciable current flow is adapted to set up a strong magnetic field in a winding which is capable of developing a strong trigger voltage pulse upon stopping of current ow and consequent breakdown of the magnetic field.

In brief, then, this invention provides power output electronic switching with low resistance input switching and electronic switch triggering by means of voltages derived from the breakdown of magnetic fields. Further generally improved performance with particular improvement in increased power handling ability over the apparatus of Fig. 1 is represented by the circuits and apparatus of Fig. 2.

In Fig. 2, grid controlled gas discharge tubes T11. Tin, Tn, and T14 familiarly known as thyratrons, or their equivalent, are employed in a multiphase oscillator circuit forming an electronic switch ESI. As is well-known, a thyratron tube will remain non-conducting or deionized, and therefore act as an open circuit, under a sufiiciently large fixed negative bias until a positive grid or trigger voltage reduces the negative bias to a point characteristic of the tube whereupon the tube becomes conductive and remains conductive until the anode voltage is cut olf. When ionized the tube is equivalent to a switch of low resistance as there is a very low voltage drop across the thyratron. Therefore, a sequence of thyratrons employed in an electronic switch must have an anode current supply, an initial grid voltage, a trigger or tiring grid pulse or voltage, and means for cutting oi anode current or otherwise restoring the tubes to initial or non-conducting condition.

A directional antenna array A-B-C-D adapted for sequence switching of its elements is coupled by a transformer Pai-S21 tuned by condenser C1 into a radio amplifier 38 connected also with non-directional antenna 6, and the output of amplifier 38, preferably of the superheterodyne type, is coupled by a transformer P22-S22 tuned by condenser C4 with a rectifier circuit including a diode rectifier T5. The direct current output of diode T5 filtered by resistance R4 and capacity C5 is applied across grid and cathode elements of a power amplifier tube Te which has a relatively high resistance R connected between grid and cathode connection 30 and has an anode current supply from +Eb of the order of 300 volts. The cathode connection 3U of tube Te returns to ground and negative of the anode current supply through a circuit including resistance and may be any one of the trigger circuits of electronic switch ESI, depending upon which one of the thyratron tubes T11-T14 is conducting. If, for example, one of the identical switch stages is conducting, say that including thyratron tube T11, cathode connection 3D of tube Te returns to ground through resistor R51, tube T11, coil P11 and diode D1 and the total resistance of this circuit becomes the cathode resistance familiar in conventional amplifiers.

Tube Ts has an anode potential of the order of 300 volts from +Eb and has a cathode connection 30 resistance to ground through load resistors R51, R52, R53 and R54 each having a resistance of about 2500 ohms. Resistors Rc1, Rs2, Re: and R64 are relatively high, for example, 20,000 ohms, and resistors R65 and Rss are relatively low, for example, 50 ohms, thus providing a negative potential on diodes D1-D4 when the corresponding thyratron is not conducting, negligible circuit resistance being added by any one of thyratron tubes T11-T14 when conducting and its respective cathode circuit coil P11-14.

As hereinbefore mentioned, a conducting thyratron is not deionized or restored to non-conducting condition without some means of cutting oii anode current supply or an equivalent. Here, anode current supply for thyratrons T11-T14 is conveniently cut off by means of a blocking oscillator 26 capable of delivering a short negative pulse of high amplitude to the grid of tube To thereby cutting off conduction and instantaneously reducing the potential of cathode connection 30 to zero with respect to ground. One form of blocking oscillator represented by 26 comprises a triode oscillator tube Ta having a grid coll Sa with grid condenser Cs and grid leak Ra and a plate feedback coil P2 inductively coupled with grid coil S3 and also inductively coupled with a voltage take-off coil S2. A negative voltage developed in coil S2 applied to the grid of tube ATe through resistor R20 while a positive voltage is clipped or limited by conduction of a diode T1 connected across coil S2. The negative voltage pulse derived from coil S2 and applied to the grid of tube Ts may be shaped or controlled in duration to a few microseconds by any suitable means as by selecting values for resistor Rza and condenser Cs which may have values of .5 megohm and 100 mmf. respectively.

Another important service of blocking oscillator 26 is the accurate timing of each sequence step of the electronic switch ESI. As will be described, each of successive thyratrons T11-T11 fires or conducts immediately after its preceding stage con types. A rectifier, such as D1, may be selected5 u has nred and been cut oli and it will be clear that the cut-oli intervals accurately determined by the blocking oscillator 26 will accurately control the time interval of each sequence step of the electronic switch ESI. In a system such as the sampling of signal strength from successive elements of a directional antenna array, it is obviously important to maintain the time duration of each sample equal as well as register its amplitude or intensity.

Having described the conductive operation and cut-oii` of a thyratron in electronic switch ESI, the trigger operation of successive stages will be explained. Initially, the grid controlled discharge tubes or thyratrons T11-T14 have their grids maintained at a negative potential from a supply -Ec through preferably low resistance coils S11-S14 and no thyratrons of electronic switch ESI are conducting. The electronic switch ESI may be started by any convenient means as by momentarily grounding the grid of thyratron T11 making same iire or conduct until anode potential is removed by the blocking oscillator action on the grid of tube Te described hereinbefore. When thyratron T11 ceases to conduct, the drop of current in coil P11 induces a positive pulse in coil S11 causing thyratron T12 to conduct. again until anode current cut-oi by blocking oscillator 26, whence in similar fashion thyratron T13 conducts then triggers thyratron T14 with conduction and triggering continuing in recurring sequence through the successive stages of electronic switch ESI. Condensers C21 improve the positive voltage pulse characteristics applied to the thyratron grids, and it may be noted that any negative pulse existing is immaterial since thyratron grids are initially made negative.

The appreciable output power of electronic switch ESI is applied to coils of an electro-magnetic indicator device I having a plurality of pole pieces such as 32a and 32h and a freely rotatable magnetic member carrying an indicating pointer 3 I a. Coil terminals K-L-J-M of indicator device I connect respectively to the anodes of thyratrons T11-T12-T13-T14 Supplied with power through resistors R51-R54. When any thyratron conducts, its corresponding coil terminal connection is short circuited to ground through the conducting thyratron. For example, when thyratron T11 conducts, terminal K is practically shorted to ground and current from the cathode conection 30 of tube Ts flows through load resistor R52 and terminal L through indicator I coils to terminal K and ground. Similarly, current now in the indicator I coils may be from terminals K to L, M to J, or J to M depending upon which thyratron of electronic switch ESI is conducting. These sequence current flows in coils of indicator I, with preferably some electric current damping provided by condensers C5 inelectronic switch ES I, set up a magnetic field controlling the position and direction indication of pointer 3Ia of indicator I. It is remembered that the applied potential from the cathode connection 30 of tube T6 is controlled by radio signal strength and thereby controls the strength and direction ol the magnetic field of indicator I and the position of pointer 3 Ia.

Input switching of elements of the directional antenna array A-B-C-D is also accomplished by electronic switch ESI in conjunction with rectier circuits including resistors R11-R14, direct current blocking condensers C11-C11 and rectifier elements D1-D4 which may be diodes or equivalent crystal rectifiers such as germanium or silias having a very high resistance or poor conductivity unless an actuating positive voltage is applied causing said rectifier to show a low resistance and good conductivity. When thyratron T11 of electronic switch ESI conducts, a positive voltage appears across resistor R61 which is applied through resistor Rn to rectier Dt making said rectier D1 a good conductor and effectively connecting antenna element A in the primary input circuit including primary coil P21 coupled with coil S21 tuned by condenser C1 at the input of radio amplifier 38. Similarly, when any one of the other thyratrons of switch ESI conducts, its corresponding rectier of Di--D4 and antenna element of A-C is activated and coupled to the input of radio amplifier 38. The combination antenna signal input to radio amplifier 38 of an element of directional antenna array A--D with that of a non-directional antenna 6 provides a desirable directional wave pattern, though any other antenna system may be switched by the apparatus provided.

Although separately described, it will be understood that electronic switch ESI and associated apparatus accomplishes simultaneous step by step control, in recurring sequence, of antenna input to radio amplifier 38 and its developed power output to a direction indicating electromechanical indicator I. Further, the time interval of each step is accurately controlled and the directional magnetic eld strength developed in indicator I corresponds exactly with the directional intensity of a received radio signal.

It is characteristic of all of the modifications of the invention that amplification of the signal voltages is effected in a single channel only thus eliminating any errors or inaccuracies which might arise from lack of exactness in mutual conductance of tube elements due to initial difference in tube characteristics or to the eiect of aging, variation in anode or heater potentials and the like. The signal voltages thus amplified in a single channel are successively applied to a plurality of independent load elements actuating the indicator to give an integrated response to the incoming signals. Any variations in the amplifier channel will affect all of the amplified signals identically and will thus be balanced out in the integrated response.

A modification of the apparatus of Fig. 2 by adding to it the elements shown in Fig. 2a may be made for purposes such as airport control work wherein it is desired to obtain from a ground or airport control tower installation an instantaneous and continuous fix or location of an incoming airplane. By providing a second directional antenna array ABZ-CD2 with a second indicating device I2 and second electronic switch ES2, all equivalent units duplicating the single units hereinbefore described with reference to'Fig. 2, dual directional readings may be taken from different receiving points fixing direction and distance by intersection of the two directional readings relative to the receiving points and the known airport lay-out. Indicators I and I2 may be mounted together for convenient reading and electronic switch ES2 may be coupled into electronic switch ESI by opening jumper 21 and connecting lead 28 with lead 28 and lead 28 with 29' and also connecting cathode connection 30 of tube Ts with switch ES2 at lead 30. Switches ESI and ES2 are then combined in a sequence of eight instead of four switch stages providing operation of the dual input and output direction indicator with a single radio amplifier 38. Each indicator and its related antenna array employs one-half of the time of the combined electronic switch and radio amplifier 38, but the available switch power output is adequate for operation of a plurality of instruments. Dual direction indications have considerable value in air and water navigation and the combination herein described illustrates the usefulness and adaptability of the apparatus of this invention.

The term indicating device used in the description and claims hereof may include means whereby the integrated response of the coil windings actuate any suitable control device and the directional indication provided by the invention may include or consist solely in the responses of such control device.

It is to be understood that the invention is not limited to the particular circuit arrangements or to the particular values herein recited and that there is considerable latitude in the circuit arrangement and circuit element constants of indicating systems that fall within the spirit of my invention as set forth in the following claims.

This application is a continuation-in-part of my application Ser. No. 559,642, illed October 20, 1944, now abandoned.

I claim:

l. An electronic direction-indicating system comprising an antennae array providing a plurality of directional antenna circuits, a single radio amplifying channel, an indicating device including a plurality of windings and pointer means movable in response to the magnitude and sense of currents in said windings, and means for cyclically connecting said antennae circuits to said amplifying channel and synchronously connecting the amplifying channel to a corresponding terminal of said windings through low-resistance non-amplifying circuit elements comprising a series succession of electronic tube stages corresponding in number to the number of said winding terminals, and connections between said tube stages for establishing conduction in one stage upon the cessation of conduction in the r preceding stage.

2. An electronic direction-indicating system comprising an antennae array providing a plurality of directional antenna circuits, a single radio amplifying channel, an indicating device including a plurality of windings and pointer means movable in response to the magnitude and sense of currents in said windings, and means for cyclically connecting said antennae circuits to said amplifying channel and synchronously connecting the amplifying channel to a corresponding terminal of said windings through low-resist ance non-amplifying circuit elements comprising a series succession of electronic tube stages corresponding in number to the number of said winding terminals, and magnetic inductive connections between said tube stages Ifor establishing conduction in one stage upon the cessation of conduction in the preceding stage.

3. An electronic direction-indicating system comprising an antennae array providing a plurality of directional antenna circuits, a single radio amplifying channel, an indicating device including a plurality of windings and pointer means movable in response to the magnitude and sense of currents in said windings, and means for cyclically connecting said antennae circuits to said amplifying channel and synchronously connecting the amplifying channel to a corresponding terminal of said windings through low- 75 resistance non-amplifying circuit elements comprising a series succession of thyratrons corresponding in number to the number of said winding terminals, a common connection between said amplifying channel and said thyratrons including negative pulse generating means for periodically blocking anode potential supply to said thyratrons, and connections between said thyratrons for establishing conduction in a succeeding thyratron upon cessation of conduction in a preceding thyratron in the series.

4. An electronic direction-indicating system comprising an antennae array providing a plurality of directional antenna circuits, a single radio amplifying channel, an indicating device including a plurality of windings and pointer means movable in response to the magnitude and sense of currents in said windings, and means for cyclically connecting said antennae circuits to said amplifying channel and synchronously connecting the amplifying-channel to a corresponding terminal of said windings through lowresistance non-amplifying circuit elements cornprising a series succession of thyratrons corresponding in number to the number of said winding terminals, a common connection between said amplifying channel and said thyratrons including negative pulse generating means for periodically blocking anode potential supply to said thyratrons, and magnetic inductive connections between said thyratrons for establishing conduction in a succeeding thyratron upon cessation of conduction in a preceding thyratron in the series.

5. An electronic direction-indicating system comprising an antennae array providing a plurality of directional antenna circuits, a diode in each of said antennae circuits, a single radio amplifying channel, an indicating device including a plurality of windings and pointer means movable in response to the magnitude and sense of currents in said windings, and means for cyclically connecting said antennae circuits to said amplifying channel and synchronously connecting the amplifying channel to a corresponding terminal of said windings through low-resistance non-amplifying circuit elements comprising a series succession of electronic tube stages corresponding in number to the number of said winding terminals, and connections between said tube stages for establishing conduction in one stage 12 uaon the cessation of conduction in the preceding s age.

6. An electronic direction-indicating system comprising an antennae array providing at least three directional antennae circuits, a diode in each of said antennae circuits, a single radio amplifying channel, an indicating device including a plurality of windings and pointer means movable in response to the magnitude and sense of currents in said windings, and means for cyclically connecting said antennae circuits to said amplifying channel through said diodes and synchronously connecting the amplifying channel to a corresponding terminal of said winding through low-resistance non-amplifying circuit elements, comprising a series succession of electronic tube stages corresponding in number to the number of said winding terminals, connections between said tube stages for establishing conduction in one stage upon cessation of conduction in the preceding stage, a source of voltage, and circuit elements for connecting said voltage source across each of said diodes in succession through the corresponding tube stage during its conductive period.

7. An electronic direction-indicating system comprising an antennae array providing four directional antennae circuits, a diode in each of said antennae circuits, a single radio amplifying channel, an indicating device including a plurality of windings and pointer means movable in response to the magnitude and sense of currents in said windings, and means for cyclically connecting said antennae circuits to said amplifying channel through said diodes and synchronously connecting the amplifying channel to a corresponding terminal of said winding through lowresistance non-amplifying circuit elements, comprising a series succession of four electronic tube stages, connections between said tube stages for establishing conduction in one stage upon cessation of conduction in the preceding stage, a source of voltage, and circuit elements for connecting said voltage source across each of said diodes in succession through the corresponding tube stage during its conductive period.

JOHN R. STEINHOFF.

No references cited. 

